Hundreds of thousands of motorists are pulled over annually because a light bulb is burnt out on their vehicle. These unscheduled and unexpected inspections frequently lead to more serious fines than those for having a burnt out light bulb. Last year Honda recalled 440,000 cars because of the safety hazard resulting from headlamps going out and the driver being unaware of the problem.
Some luxury vehicle manufacturers have ran fiber optic cable from individual lights to a location visible to the driver. But these fiber optic cables are difficult to run and maintain in operative position. Additionally they must be viewed at the time the light should be operating. Cadillacs have rear brake monitor indicators positioned inside the vehicle above the rear window. Few motorists look in their rear view mirror while they are braking. Honda uses a 2 second diagnostic test to check brake lights when the vehicle is started. The test only ensures that at least one of the four light bulbs is operative. There is no indication which light is burnt out, and there is no indication while one is driving.